chore(general): add healthz-related metrics

cmd/base/context.go

@@ -189,7 +189,7 @@ func NewGenericContext(
 			Handler: httpHandler.WithHandleChain(mux),
 			Addr:    genericConf.GenericEndpoint,
 		},
-		healthChecker:             NewHealthzChecker(),
+		healthChecker:             NewHealthzChecker(customMetricsEmitterPool.GetDefaultMetricsEmitter()),
 		DisabledByDefault:         disabledByDefault,
 		MetaInformerFactory:       metaInformerFactory,
 		KubeInformerFactory:       kubeInformerFactory,
@@ -266,14 +266,8 @@ func (c *GenericContext) StartInformer(ctx context.Context) {
 // serveHealthZHTTP is used to provide health check for current running components.
 func (c *GenericContext) serveHealthZHTTP(mux *http.ServeMux, enableHealthzCheck bool) {
 	mux.HandleFunc(healthZPath, func(w http.ResponseWriter, r *http.Request) {
-		if !enableHealthzCheck {
-			w.WriteHeader(200)
-			_, _ = w.Write([]byte("healthz check is disabled"))
-			return
-		}
-
 		ok, content := c.healthChecker.CheckHealthy()
-		if ok {
+		if ok || !enableHealthzCheck {
 			w.WriteHeader(200)
 			_, _ = w.Write([]byte(content))
 		} else {

cmd/base/healthz.go

@@ -19,25 +19,45 @@ package katalyst_base
 import (
 	"context"
 	"encoding/json"
+	"time"
 
 	"go.uber.org/atomic"
+	"k8s.io/apimachinery/pkg/util/wait"
 
+	"github.com/kubewharf/katalyst-core/pkg/metrics"
 	"github.com/kubewharf/katalyst-core/pkg/util/general"
 )
 
+const (
+	syncPeriod              = 30 * time.Second
+	MetricNameUnhealthyRule = "unhealthy_healthz_check_rule"
+)
+
 // HealthzChecker periodically checks the running states
 type HealthzChecker struct {
 	// if unhealthyReason is none-empty, it means some check failed
 	unhealthyReason *atomic.String
+	emitter         metrics.MetricEmitter
 }
 
-func NewHealthzChecker() *HealthzChecker {
+func NewHealthzChecker(emitter metrics.MetricEmitter) *HealthzChecker {
 	return &HealthzChecker{
 		unhealthyReason: atomic.NewString(""),
+		emitter:         emitter,
 	}
 }
 
-func (h *HealthzChecker) Run(_ context.Context) {}
+func (h *HealthzChecker) Run(ctx context.Context) {
+	go wait.Until(func() {
+		results := general.GetRegisterReadinessCheckResult()
+		for key, result := range results {
+			if !result.Ready {
+				_ = h.emitter.StoreInt64(MetricNameUnhealthyRule, 1, metrics.MetricTypeNameRaw,
+					metrics.MetricTag{Key: "rule", Val: string(key)})
+			}
+		}
+	}, syncPeriod, ctx.Done())
+}
 
 // CheckHealthy returns whether the component is healthy.
 func (h *HealthzChecker) CheckHealthy() (bool, string) {